ProteinsA protein is made of monomers called amino acids
ProteinProtein structure is determined by the number and order ofamino acids
Protein StructureThe structure of proteins are important because1. Proteins make up what our cells look like2. Proteins carry out important functions in the cell
Special ProteinsProteins that catalyze reactions (which means speed upreactions) are called enzymesExamples of enzymes picture Tyrosinase Hydrolase Lactase
Four Levels of Protein StructurePrimary Structure (1o structure)The order and number of amino acids strung together akaa polypeptide chain.
Four Levels of Protein StructureSecondary Structure (2o structure)Common shapes found in all proteins made from hydrogenbonds such as alpha helices and beta pleated sheets
Four Levels of Protein StructureTertiary Structure (3o structure)The three dimensional (3-D) structure of amino acids
Four Levels of Protein StructureQuaternary Structure (4o structure)2 or more polypeptides that are folded in a 3D shape andcombined together
Warm-up* Check bacteria paintings in incubatorWhat are special proteins that speed up reactions called?Study Guide Questions#2 What is the general equation for photosynthesis#7 What are the 3 differences between mRNA and DNA#10 What is mRNA and tRNA? What is their structure andfunction in the cell?Announcements:Participation Pts announcementHonors HW due Tomorrow9 Days until ExamLab Notebooks
Protein Function• Made by all living things to perform these functions: o Structural: Hair and muscles o Immunity: Antibodies o Signaling and communication: Neurotransmitters and hormones. o Transport: Ion channels o Enzymes: Catalyze (speed up) biochemical reactions
Enzymes in our daily lives: HYDROLASE LACTASE PROTEASE
Enzymes are the ConstructionWorkers of the Cell… Enzymes help BUILD UP or BREAK DOWN molecular structures
Catalysts• Catalysts speed up chemical reactions by lowering the activation energy and are not used up in the reaction.
How do catalytic enzymes work?• Substrate binds a region of the enzyme called the active site (a pocket formed by the folding of the protein enzyme that is highly specific for the substrate).
Enzymes are usually named with the suffix –aseadded to the name of the substrate or reaction Inhibitors slow down enzymes! Paperclipase Toothpickase
Changing how enzymes workWe can change the enzymes ability to catalyze (speed up)a reaction in two ways:1. Denaturation – protein unfolding into the 1o structure1. Inhibition – preventing an enzyme from functioning 1. Competitive inhibitors – block the active site so that the substrate can not bind 2. Non-competitive inhibitors - bind to the enzyme and make them unable to bind the substrate
Why care about enzymes?• Enzyme that helps muscle cells communicate with the nervous system.• Nerve Gas inhibits acetylcholinesterase o Enzyme is used to break down the neurotransmitter acetylcholine. o When it is inhibited, paralysis and death follow. http://ucsdnews.ucs d.edu/newsrel/healt h/nihgrants06.asp
Why care about enzymes?Myasthenia Gravis is an autoimmune disease that causes an individualto suffer from severe muscle weakness. This weakness is caused by adecreased amount of nicotinic acetylcholine receptors in theneuromuscular junction. These receptors normally are activated by theneurotransmitter acetylcholine, which is also deactivated by an enzymecalled acetylcholinesterase. By inhibiting acetylcholinesterase, moreacetylcholine is available to the receptors and a normal ratio ofreceptors to neurotransmitters is established and the muscles canfunction normally. In this video a myasthenic dog, who normally hastrouble walking, is treated with an acetylcholinesterase inhibitor andcan walk and even run normally until the inhibition wears off.
ObjectiveTo extract the enzyme Tyrosinase from a Portobellomushroom in order to test the reaction rate of the enzymein normal conditions and compare it to conditions wherethe enzyme is exposed to inhibitors, increasedtemperature, or changes in pH.
The Enzyme TyrosinaseTyrosinase is an enzyme that causes pigmentation inapples, skin, hair, etc.